Originally Posted by Malek
Leather Master and Leatherique work in completely different ways. Leather Master is water based while Leatherique is not.
The M3 Steering wheel is an un-coated analine leather which responds to products like Leatherique very strongly. Leatherique simply will never work on coated leather surfaces. Every leather surface in modern BMW's today is un-coated analine, meaning that the Leatherique product will actually penetrate and do what it is intended to do, rather than work on the surface.
I personally don't like the Leather Master products much at all on BMW's, and find Leatherique to be far more effective and impressive.
If the steering wheel is not consistently cared for, it is going to be a almost impossible to return it to a 100% new look as all the oil and dirt may have actually abraded away at the leathers surface. A weekly wipe down would really aid in prolonging this from happening, but it is inevitable in the end.
This is incorrect. BMW leather is "semi-aniline," meaning it has a urethane coating as the outermost layer. "Full aniline" lacks a protective coating over the color coat. Very few modern cars utilize full aniline leather. You are correct about Leatherique being oil-based, and oil-based products should never be used on BMW leather. Water-based products like Leather Masters are what need to be used.
Regarding the steering wheel issue in the OP, the most effective way of removing contaminates from any leather surface in our cars is through steam cleaning. Steam will pull embedded contaminates off of the steering wheel and onto the towel attached to the steam nozzle. It's much more effective than cleaning the wheel by hand w/ a water-based cleaner. The steering wheel in this picture looked glossy and was full of body oils prior to being steamed. The factory, matte-look was restored: